In Magnetic Resonance Imaging (MRI), gradient amplifiers are typically used to provide current for magnetic field gradient coils to provide spatial encoding of atomic spins located in a magnetic field. These gradient amplifiers are typically characterized by high peak power and high precision of the generated current waveforms.
A significant fraction of MRI scans may only require a slew rate of the generated current waveforms lower than the slew rate initially provided by the MRI system. For those scans, the initial slew rate is reduced.
U.S. Pat. No. 5,646,835 discloses a series resonant converter which a voltage controlled oscillator and phase delay to control the switching (IGBT gating) to respond to changing load demands.